2002 Drought Summit
311 Cannon House Office Building
Washington, D.C. 20515
Robert M.
Hirsch
U.S.
Geological Survey
Associate
Director for Water
Reston,
Virginia
October 3,
2002
I would like to make a few remarks about the role that
hydrologic science can play in helping citizens and communities prepare for and
cope with drought. I will confine my
remarks to hydrologic or water supply drought, in contrast to agricultural
drought. Hydrologic and water supply
drought refers to the shortage of water available for withdrawal for uses
including: residential, municipal, agricultural, or industrial supply. It also includes the decline in flows of
springs and streams that are detrimental to: hydropower production, navigation,
recreation, or maintenance of habitat for aquatic and riparian species.
First, we must recognize that droughts are natural
phenomena. Their severity and duration
cannot be accurately predicted, although our colleagues in the atmospheric
science community are making some progress on improving the ability to predict
when they may occur. Second, we must
recognize that severe droughts will happen again. Human activities (affecting the atmosphere or landscape) may
change the pattern of severity and duration of droughts and yet, even in the
absence of scientific results that would indicate what kind of changes may take
place in the future, society must learn to expect the unexpected when it comes
to drought. The paleo-climate record
demonstrates previous drought episodes that were either longer or more severe
than any we have experienced in the few centuries of our Nation’s recorded
history.
The drought that is taking place at this time is a
significant one, especially in the Mid-Atlantic States and parts of the Great
Plains and Rocky Mountains. For some
of these areas the situation today is a continuation of generally dry
conditions that have taken place for three to four years. Many of our monitoring locations have shown
water levels or streamflows that are below all-time record lows for specific
days of the year. However, on an
overall basis we believe we are seeing a very significant drought but probably
not the “drought of the century” over any large area.
Hydrologic science helps in two ways. The first is in drought planning. The key to success in coping with water
supply drought is to assure that water can be drawn from storage to supply
water users with an adequate supply when the lack of precipitation limits the
natural flow of rivers. This storage
can include: surface-water reservoirs or aquifers. This includes traditional forms of ground-water resource
development as well as systems of artificial recharge or aquifer storage and
recovery that take advantage of excess water during wet periods or of waste
water and put it into the subsurface, to be extracted in times of the greatest
need. What hydrology brings to planning
is the knowledge of the rivers, the range of variations in flow, and the
reliable yield of reservoirs and aquifers.
This kind of information is most useful when it is organized through the
use of mathematical simulation models that can test the consequences to water
users and ecosystems of plausible future drought scenarios. State and local agencies and private
individuals who must plan for future drought use this information to evaluate
their options. USGS historical data on
streamflow, now over 100 years long and available on the Internet, are the
basis for all of these kinds of analyses.
This kind of drought planning requires a strong foundation
of information. About a year ago the
House Appropriations Committee expressed to us their concern over the “future
of water availability for the Nation . . . for growing communities,
agriculture, energy production, and critical ecosystems.” They noted that a nationwide assessment of
water availability is several decades old.
They asked the USGS to “ . . .prepare a report describing the scope and
magnitude of the efforts needed to provide periodic assessments of the status
and trends in the availability and use of freshwater resources.” That report has been delivered to the
Congress and we would be pleased to discuss the ideas that are proposed in
it. Understanding the availability of
water for the Nation is really synonymous with understanding drought, for it is
in times of drought that our society comes face-to-face with the real limits of
the available supply.
The second way that hydrologic science helps society cope
with drought is the information that can be used to help communities make the
best day-to-day management decisions while the drought is taking place. What kind of water management decisions are
possible once the drought has begun?
Some of the key decisions are these:
holding water in reservoirs to meet potentially more serious needs that
may be weeks or months in the future versus withdrawing or releasing it now to
satisfy legitimate immediate needs; increasing ground-water pumping to augment
surface-water supplies; purchase of water from neighboring jurisdictions or
users where this is feasible from an engineering and legal standpoint; and
restricting certain categories of water use.
Decision-makers need accurate and timely information on the current
status and recent trends in streamflow, ground-water level, and water use.
The USGS provides broad coverage for streamflow information
through our new Internet system known as WaterWatch (http://water.usgs.gov/waterwatch)
that you see on the briefing board beside me.
Development of real time ground-water information is only beginning to
be implemented but shows great potential.
The State of Pennsylvania has worked with the USGS for more than a
decade to develop a system they now routinely use in State drought management
applications (see http://pa.water.usgs.gov/monitor/).
In the area of water use, the information available for
managers concerned with either short-term or long-term decisions is less
developed. The National Research
Council issued a report this year regarding water use information. That report is entitled “Estimating Water
Use in the United States: A new paradigm for the National Water-Use Information
Program.” Managers also need good
probabilistic forecasts of hydrologic conditions for the coming weeks and
months. Our colleagues at the National
Weather Service are moving forward with their Advanced Hydrologic Prediction
Services, to provide just this kind of information to water managers.
The USGS is very active across the Nation, working with
State, local and tribal governments to help them plan for drought and to
function effectively during drought. We
do this principally through the Cooperative Water Program. In this program, we collect and disseminate
data on rivers and ground water, map and model aquifer units, and help to
define the water resource and predict how it will behave under the stress of
drought. A large number of the 1300
cooperating non-federal agencies with whom we work in the Cooperative Water
Program seek our help in better defining the availability of water and the
consequences of drought. By using our
national network of monitoring sites, scientific staff, and historic and
real-time databases, we are able to make valuable contributions to help them in
their mission of managing water resources in the face of drought.
As I conclude my remarks, let me compliment the Congress for
holding this session, and particularly express my appreciation to Congresswoman
Barbara Cubin. We were very pleased to
see in a prominent position on her home page the words “Click Here for the
latest information on Wyoming Drought Conditions.” Clicking there takes one directly to the USGS Wyoming Drought
Conditions page. Providing information
for drought planning and for coping with drought are important parts of our
mission at the USGS. We are pleased to
be able to provide that service to the American people and are pleased to be
recognized for doing so. We look
forward to continuing and improving these services in years to come.
I will be pleased to address any questions you may have.